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3.4.2 Task Priority and Ready Queue
In the kernel, several tasks may simultaneously request to be executed. In such a case, it is necessary to determine which
task the system should execute first. To properly handle this kind of situation, the system organizes the tasks into proper
execution priority and starts execution with a task having the highest priority. To complete task execution quickly, tasks
related to processing operations that need to be performed immediately should be given higher priorities.
The MR100 permits giving the same priority to several tasks. To provide proper control over the READY task execution
order, the kernel generates a task execution queue called "ready queue." The ready queue structure is shown in Figure
3.
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13
The ready queue is provided and controlled for each priority level. The first task in the ready queue having the
highest priority is placed in the RUNNING state.
14
1
TCB
Priority
2
TCBTCB
TCBTCB
TCB
3
n
Figure 3.17 Ready Queue (Execution Queue)
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The TCB(task control block is described in the next chapter.)
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The task in the RUNNING state remains in the ready queue.